Preparation Of Pd_xAg_yCu_z Catalyst And Study On Its Electrocatalytic Performanc

With the increasing demand of energy consumption and the worsening of environmental pollution,it is imperative to explore clean energy to replace the decreasing fossil fuels.Fuel cell is regarded as one of the promising alternative energy sources because of its high energy conversion efficiency and environmental friendliness.Pd shows excellent electrocatalytic performance in fuel cells,but its high cost and scarcity greatly limit the industrialization process.Therefore,this paper intends to synthesize efficient,stable and clean Pd-based catalysts that can be used in fuel cells system,such as these catalysts for alcohol oxidation reaction and hydrogen evolution reaction.In this paper,Cu@Pdx catalyst was prepared by one-step hydrothermal method with PVA as dispersant and soft template.The composition and morphology of Cu@Pdx catalyst are optimized by adjusting the content of Pd precursor.Among them,Cu@Pd22.3 catalyst has the smallest average particle size(1.52 nm),and these nanoparticles are further agglomerated to form a nanoflower structure until part of the nanoflowers are connected into a 3D network structure.This structure provides a large electrochemically active surface area(29.05 m2 g-1)and a large number of active sites.Cu@Pd22.3 catalyst shows excellent catalytic performance for ethylene glycol oxidation(4353.04 m A mg Pd-1),which is 13 times higer than that of commercial Pd/C.At the same time,a 42 m V overpotential for Cu@Pd22.3 catalyst is much lower than a56 m V overpotential for the commercial Pd/C in the hydrogen evolution reaction.In addition to the morphology and size characteristics of the catalyst,the synergistic effect between Pd and Cu is also attributed to the optimization of the surface electronic structure to reduce the adsorption of Co-like substances on the Pd surface.Furthermore,Ag was added into the catalyst by the same method.The results show that the Pd Cu alloy has a nano-flower shape,attach to the metal chain formed by Ag,and evolve into a more complex 3D network structure.The mass activity of Pd Ag4 Cu catalyst for ethylene glycol oxidation(9654.39 m A mg Pd-1)is higher than that of Cu@Pd22.3 catalyst.In addition,the catalytic performance of Pd Ag4 Cu catalyst for hydrogen evolution reaction is better than that of Cu@Pd22.3 catalyst.The overpotential Cu@Pd22.3 catalyst(25 m V)is much lower than that of commercial Pd/C(56m V)and comparable to that of commercial Pt/C(31 m V).On the one hand,the 3D network structure formed by the incorporation of Ag is more compact,which is more conducive to electron transmission in the reaction process.On the other hand,the structure of Pd Cu alloy and the optimized synergistic effect between different components are beneficial to the rapid reaction kinetics.